Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by pretreatment with carbon dioxide. The carbon dioxide pretreatment is believed to convert the scale-forming components to the corresponding ca

A novel process, and the compositions of matter formed thereby, wherein Group II-A metals, or compounds thereof, can be ion-exchanged onto coal, preferably a high rank coal, notably a subbituminous or bituminous coal, by soaking the coal in an alkali solution of a Group I-A metal compoun

The production of liquid hydrocarbons from coal is significantly enhanced by alkylating or acylating the coal prior to subjecting the coal to liquefaction conditions. The introduction of aliphatic hydrocarbon radicals or acyl radicals, including carbon monoxide, into the coal structu

A slurry of coal solids or similar carbonaceous material substantially depleted in mineral-rich particles is prepared for delivery to any desired place of use by introducing particulate coal and a suitable carrier liquid into a slurry preparation zone; passing a stream of slurry from the